Yes, we are testing in WSL environment. On removing the mount mark, git clone succeeds.
We are using the releases from: https://github.com/microsoft/WSL2-Linux-Kernel/releases
Did u get to try git clone operation on 9p mount on your setup ? May I know the kernel version ?
Can you share the commands of how you created a 9p mount on your test box ?
Please find the code for rename(attached), execute and share the result in 9p mount of ur setup.
I have tested the fanotify example. It is working in WSL environment. Infact even, in the example code, I have marked only with FAN_CLOSE_WRITE mask. This event handler is recognizing the event and printing it.
Thank you,
Krishna Vivek
-----Original Message-----
From: Amir Goldstein <amir73il@xxxxxxxxx>
Sent: Tuesday, September 24, 2024 2:27 PM
To: Krishna Vivek Vitta <kvitta@xxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx; jack@xxxxxxx
Subject: Re: [EXTERNAL] Re: Git clone fails in p9 file system marked with FANOTIFY
On Tue, Sep 24, 2024 at 7:25 AM Krishna Vivek Vitta <kvitta@xxxxxxxxxxxxx> wrote:
>
> Hi Amir
>
> Thanks for the reply.
>
> We have another image with kernel version: 6.6.36.3. git clone operation fails there as well. Do we need to still try with 5.15.154 kernel version ?
No need.
>
> Currently, we are marking the mount points with mask(FAN_CLOSE_WRITE) to handle only close_write events. Do we need to add any other flag in mask and check ?
No need.
>
> Following is the mount entry in /proc/mounts file:
> C:\134 /mnt/c 9p
> rw,noatime,aname=drvfs;path=C:\;uid=0;gid=0;symlinkroot=/mnt/,cache=5,
> access=client,msize=65536,trans=fd,rfd=4,wfd=4 0 0
I don't know this symlinkroot feature.
It looks like a WSL2 feature (?) and my guess is that the failure might be related.
Not sure how fanotify mount mark affects this, maybe because the close_write events open the file for reporting the event, but maybe you should try to ask your question also the WSL2 kernel maintainers.
I have tried to reproduce your test case on the 9p mount on my test box:
v_tmp on /vtmp type 9p (rw,relatime,access=client,msize=262144,trans=virtio)
with fanotify examples program:
https://manpages.debian.org/unstable/manpages/fanotify.7.en.html#Example_program:_fanotify_example.c
and could not reproduce the issue with plain:
echo 123 > x && mv x y && cat y
>
> Attached is the strace for failed git clone operation(line: 419, 420).
All the failures are ENOENT, which is why I suspect maybe related to the symlinkroot thing.
> Even I wrote a small program to invoke rename, followed with open.
> The open fails immediately and succeeds after 3-4 iterations.
> This exercise was performed on p9 file system marked with fanotify.
Please share your reproducer program.
The difference could be in the details.
Can you test in a 9p mount without those WSL options?
Can you test on upstream or LTS kernel?
Can you test with the fanotify example?
>
> Am not reporting this as regression. We havent checked this behavior before.
>
Ok. patience, we will try to get to the bottom of this.
Thanks,
Amir.
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
int main() {
const char *filename = "config.lock";
const char *new_filename = "config";
const char *content = "Hello, this is a test with file rename operation.\n";
char buffer[100];
int fd;
ssize_t bytes_read;
int counter=0;
// Delete the file if it already exists
if (access(new_filename, F_OK) != -1) {
if (remove(new_filename) != 0) {
perror("Failed to delete existing file");
//return EXIT_FAILURE;
}
}
// Create a new file and write to it
fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0644);
if (fd == -1) {
perror("Failed to create file");
return EXIT_FAILURE;
}
if (write(fd, content, strlen(content)) == -1) {
perror("Failed to write to file");
close(fd);
return EXIT_FAILURE;
}
close(fd);
// Rename the file
if (rename(filename, new_filename) != 0) {
perror("Failed to rename file");
return EXIT_FAILURE;
}
// Open the renamed file and read the content
fd=-1;
/*
while(fd==-1) {
fd = open(new_filename, O_RDONLY);
counter++;
}
printf("File appeared in %d iterations\n", counter);
*/
fd = open(new_filename, O_RDONLY);
if (fd == -1) {
perror("Failed to open renamed file");
return EXIT_FAILURE;
}
bytes_read = read(fd, buffer, sizeof(buffer) - 1);
if (bytes_read == -1) {
perror("Failed to read from file");
close(fd);
return EXIT_FAILURE;
}
buffer[bytes_read] = '\0'; // Null-terminate the buffer
close(fd);
// Print the content
printf("Content of %s:\n%s", new_filename, buffer);
return EXIT_SUCCESS;
}
